Adjustable tool.



PATENTBD APR. 30, 1907.

R. T. JOHNSTON.

ADJUSTABLE TOOL;

APPLIOATION FILED HAD. 6 1905 2 SHEETS-SHEET 1.

mt'rzcases afl t PATENTED APR. 30 1907.

ROBERT T. JOHNSTON, OF TAUNTON, MASSACHUSETTS.

ADJUSTABLE TOOL.

Specification of Letters Patent.

Patented fipril 30, 1907.

Application filed March 6,1905. Serial No. 248,535.

To all whom it may concern:

Be it known that I, ROBERT T. JOHNSTON, a citizen of the United States,residing at Taunton, in the county of Bristol and State ofMassachusetts, have invented a new and useful Adjustable Tool, of whichthe following is a specification.

The object of this invention is to provide a new and improved adjustabletool such as a reamer, arbor, tap, etc. and, while the invention iscapable of this general application, as hereinafter described, it hasbeen more particularly designed as an adjustable reamer.

Reamers are now made solid; that is of one piece of metal, but thesehave the disadvantags that when worn they have to be discarded. Reamersare also made adjustable for wear, in several ways. One way is to make abody or shell of low grade steel and to secure a plurality of blades orcutting edges thereto by screws. When the blades wear down, they areremoved, packed up with pa per or shims, and then again secured in placeand reground to size. A serious objection exists to this style ofreamer, in that if paper is used, the same absorbs moisture and oil anddoes not hold its size, and, in that the reamer is not as solid as asolid reamer, the screws being liable to loosen.

Another type of adjustable reamer has its blades laced in dove-tailedgrooves, the bot-- toms 0 which are at a slight angle to the axis of thereamer. When the reamer wears down, the blades are driven or adjusted upand the reamer thus expanded. The reamer is reground after the bladesare adjusted. A serious objection to this style of reamer exists in,that as it is handled in use, the posi .tion' of the blades may bechanged from one cause or another and thus the adjustment alteredor elsethe size of the reamer can be changed by an unauthorized workman.

As a reamer is a tool for finishing holes to a standard size, theobjections above noted are very serious.

Another objection that exists to adjustable reamers is that they chatterand do not make a smooth hole. The nearer solid an adjustable reamer canbe made, the less it will chatter. V

I The object of this invention is to overcome these ditliculties and tomake an adjustable tool, particularly a reamer, so that it may beadjusted after it is worn without the above objections. To accomplishthis desirable result, provide the body or shell with a plurality or aseries of grooves parallel to the axis of the reamer, the bottoms orseats of said grooves being arranged at difl'erent distances from thecenter, which varying distances are preferably arranged in regularprogression.

The blades are made of corresponding varying thicknesses so that wheninserted in position they will match with the grooves, whereby the outeror cutting edges thereof will form a true cylindrical surface relativelyto the axis of the tool. The grooves are preferably made dove-tailed inshape and the blades are made to fit said grooves so that they can bedriven tightly in place.

\Vhen the reamer is worn and is to be adjusted, the blades are removedand the thinnest blade is discarded and a new blade of the largest sizeinserted in the deepest groove and the other blades movecircumlerentially around the body. -Alter the blades are socured inposition in this way, the reamer is reground to accurate size. in thisway, when itis desired to adjust the reamer, only one blade has to bediscarded and as ditlerent adjustmentstake place, each new blade will beused in each of the grooves in progression. method of adjustment isobtained.

The invention is capable of application to arbors and taps and othercylindrical tools which require rigidity in use and which have to beadjusted, for wear.

The accompanying two sheets of drawings 9 illustrate the way theinvention may be practiced.

Referring to the drawings and in detail, Figure 1 is an end view of area mer constructed to embody my invention. spective view showing themethod of adjustment. Fig. 3 is a perspective view of the new bladeemployed. Fig. 4 is a view similar to Fig. 1 showing a modification inwhich each blade has two cutting edges. a similar view illustrating myinvention ap plied to an arbor. Fig. 6 is a perspective view showing themethod of adjustment and, Fig. 7 is a sectional view showing one way ofholding the blades to the body.

Referring to the drawings and in detail, A designates the body whichmaybe made in the form of a cylindrical shell and which has a transversekey-seat. A plurality of dovetailed grooves is cut in said shell.

In this manner, an economical Fig. 2 is a per- Fig. 5 is I In the 11specific illustration shown in the figures, eight of such grooves areshown. grooves are cut of different ,radial depths, which depthsincrease in regular progressions or, in other words, the seats orbottoms of the same are arranged parallel on a spiral cylinder,'asindicated by the dotted line S. A series of blades B is inserted in saidgrooves. These blades are made to fit said grooves and of relativelyincreased thickness so that when inserted in position, their outsideedges will coincide with the surface of a true cylinder, as indicated bythe dotted line C, in Fig. 1. The bottoms or seats of said grooves aremade of the same width sov that any blade, no matter what its thickness,wilLfit into any one of the grooves.

The blades are held to the body in any desired way, as by driving" themtightly in place, by screws, or by the usual shaft as shown in Fig. 7,which shaft lO-has a collar 11 to engage one end of the blades, a key 12to engage the key-seat in the body or shell, and a removable collar 13on the other end, which is held in place by a nut 14 threaded on the endof said shaft.

When the rearner has become worn or when it is desired to adjust thesame, the blades are removed and a new blade, of the largest thickness,as shown in Fig. 3, is inserted in the groove of the largest depth andthe blades are re-inserted in the body, one groove in advance from theposition they previously occupied, counting from the deepest groove tothe shallowest groove.

. The thinnest blade which is thus crowded out is discarded.

The blades are then secured in their new positions and are reground. Inthis way, a reamer which is as solid as'is possible, is provided and anad-- These The invention is of particular use in connection with arborsas, if the progression in the depth of the grooves is made small, littleor no grinding is necessary for adjustment.

The details and arrangements herein described may be greatly varied by askilled mechanic without departing from the scope I of my invention.

Having fully described my invention, what I desire to secure byLetters-Patent is z 1. The combination of a body having a plurality ofseats arranged at varying dis tances from the center and a plurality ofinterchangeable blades therefor, said blades having means wherebytheircutting edges will be located at equal distances from the axis ofthebody when the blades are in position in the seats.

2. The combination of a body having .a plurality of seats arranged atvarying distances from the center and a plurality of interchangeableblades of different thicknesses rality of blades adapted .to fitremovably in 4 said seats, said blades being of varying thicknesses,whereby their cutting edges will be at equal distances from the axis ofthe body when they are in position in the seats.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

ROBERT T. JOHNSTON.

Witnesses:

C. J. RO ERTSON, FRED J. VIEWEG.

